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On Monday, the Supreme Court allowed the nationwide legal confusion to continue regarding a bread-and-butter privacy topic in the digital age: whether the constitution demands that the authorities need a probable cause court warrant to obtain cell-site location data records of suspects under investigation.

That's because the justices, without comment, declined (PDF) to consider the case of Florida man Quartavious Davis who got a life term for several robberies in a 2010. Prosecution in that trial built its case with Davis' mobile phone's location data, which the police obtained without a warrant from mobile provider MetroPCS. The data linked the man to several crime scenes. The government's position on the topic is that Americans' mobile devices can be tracked without the Fourth Amendment's probable case standard being met.

For the moment, there is no clear legal standard on whether a warrant is required. Two federal appellate courts have ruled that no warrant was necessary (PDF), but a third appeals court said that warrants are required. That divergence of views normally is enough to create a so-called "split" in the appellate courts, which would necessitate Supreme Court intervention to resolve the conflict. But the 4th US Circuit Court of Appeals, which ruled in favor of privacy, set aside (PDF) its decision two weeks ago and agreed to rehear the issue.

That means there's no split in the circuits, and courts in the majority of the nation are free to rule as they see fit on the issue. For the privacy minded, this uncertainty is a big deal.

For starters, cell-site tracking has become extremely important to crime fighting in the wake of the high court's 2012 ruling that they need a warrant to place GPS trackers on vehicles. Equally important, in all the cases on the cell-site location tracking, the government argues that cell-site records are not constitutionally protected. Instead, the authorities maintain that they are business records that the telcos may hand over if the government asserts that reasonable grounds exist to believe the data is relevant to an investigation.

That position is based on Supreme Court precedent dating to 1979 from a case known as Smith v. Maryland. That case has justified the legal underpinnings for the National Security Agency's telephone metadata snooping program—the program NSA whistleblower Edward Snowden exposed.

In Davis' petition (PDF) to the justices, his attorneys at the American Civil Liberties Union said that 1970s precedent is outdated.

"It is virtually impossible to participate fully in modern life without leaving a trail of digital breadcrumbs that create a pervasive record of the most sensitive aspects of our lives. Ensuring that technological advances do not ‘erode the privacy guaranteed by the Fourth Amendment’ requires nuanced applications of analog-age precedents," the petition said.

The legal flap is about MetroPCS records from August 1, 2010 to October 6, 2010. Davis dialed dozens of numbers each day. The data provided to the authorities without a probable-case warrant included the dialed numbers of calls made by and to his phone, and the date, time, and duration of those calls.

Central to the dispute is data about the cell tower that wirelessly connected the calls from and to Davis, including the location of those towers.

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David Kravets
The senior editor for Ars Technica. Founder of TYDN fake news site. Technologist. Political scientist. Humorist. Dad of two boys. Been doing journalism for so long I remember manual typewriters with real paper. Emaildavid.kravets@arstechnica.com//Twitter@dmkravets